The invention resides in a method and arrangement for controlling a ship propulsion system wherein, in a first operating mode, the position of a command signal generator is interpreted in a forward position range or in a reverse position range by a controller as a desired direction of travel as well as a desired power output value of a drive engine.
A ship propulsion system comprises mechanical drive components, typically a combustion engine, a transmission and a drive arrangement in the form of a fixed or an adjustable propeller or a water jet. The operator or captain sets the direction of travel or movement of the ship and the desired power output by pivoting a command lever from a neutral position for example to a forward or reverse movement position by an appropriate angle. By a system controller, the pivot direction, in this case, forward and the pivot angle is detected wherein the latter is interpreted as desired engine power output. The pivot direction and the desired power output then supplied by the system controller as desired values to an electronic engine control unit and to an electronic transmission control unit. The navigation of a ship in a narrow harbor however is critical in praxis since even small adjustments of the command lever are entered by the system controller as desired values and converted by the ship propulsion system into a corresponding thrust. In a double drive system including two combustion engines; it may additionally occur that the two command levers are unintentionally in different positions resulting in different thrusts.
DE 10 2005 001552 A1 discloses a control arrangement with a low speed mode and a rapid speed mode. The slow speed mode is activated when the command lever is disposed in a neutral switch-over range between a forward and a reverse setting position. Outside this range, the rapid speed mode is activated. The forward switch-over position and the reverse switch-over position are defined via mechanical engagement functions. If this control lever is pivoted from the neutral range position to the forward movement position, upon movement out of the neutral position, a corresponding engine drive speed is indicated. If the captain demands only a short time power output he has to pivot the control lever in a first step manually for example in forward movement direction and, in a second step back into the neutral position and, under certain circumstances, in a third and fourth step, he may have to do this similarly in reverse direction. This is critical during docking and also during take-off of the ship so that the control arrangement and the method disclosed is not optimal for all maneuvers.
It is the object of the present invention to provide an improved method and arrangement for controlling a ship propulsion system.